diff --git a/_config.yml b/_config.yml
index 77f82f14d2..f4c1c9c7a2 100644
--- a/_config.yml
+++ b/_config.yml
@@ -17,10 +17,9 @@ rss:              RSS
 remote_theme: sighingnow/jekyll-gitbook
 
 toc:
-  enabled:       true
-  enabled_index: true 
-  h_min:         1
-  h_max:         3
+  enabled: true
+  h_min:   1
+  h_max:   3
 
 # customize the link favicon in header, will be {{site.baseurl}}/{{site.favicon_path}}
 favicon_path:     /assets/gitbook/images/favicon.ico